I understand that Spycraft is published under OGL. That means the game itself is free and the copyrights apply mainly to names, artwork etc.

But not being a lawyer that still remains a bit on the unclear site. Exactly what and how, and what legal notes (apart from the copy of OGL) do I need to include with my product.

The product I prepared I a Codebook for the players in my campaign, but the book includes a character sheet (not copy/paste way, designed by me, but with all the elements as per the original one. The book does not include any names (other than Skills etc). I am thinking of publishing it for the wider community to enjoy, but I'm just not to sure if I can.

There's a whole range of things no one considers when thinking about the OGL, and a lot of things you still can't legally do even with an OGL game. The best way to slip right past all of them is to simply score a Powered by Spycraft license.

It requires approval but assuming what you're trying to do is supporting the game rather than undermining it that shouldn't be an issue - and best of all, it's entirely free.

We'll watch for your application.

P.S. If you're still unsure what to do, drop me a line and we'll chat about the specifics of your project.